A first transistor is called stronger than a second transistor when the driving capability of the first transistor is larger than that of the second transistor. Explained in a different way, the saturation current of the first transistor is higher than that of the second transistor when the voltage potentials on ports of both transistors are the same.
In one approach, an inverter is used at the output stage of a word line driver. The inverter includes a PMOS transistor and an NMOS transistor. The output of the inverter provides a signal for the word line. Based on the operation of the word line driver, when the word line is activated, the voltage at the gate of the NMOS transistor is higher than the voltage at the source of the NMOS transistor. As a result, the NMOS transistor is not fully off, and generates leakage current. The PMOS transistor is designed to be stronger than the NMOS transistor to compensate for the leakage current from the NMOS transistor. As a result, the range for the voltage at the source of the NMOS transistor is limited by the threshold voltage of the NMOS transistor. Further, die sizes for the PMOS transistor and thus for the output stage of the word line driver are large.
Like reference symbols in the various drawings indicate like elements.